Final answer:
To change the sentence 'She isn't always clever' into an affirmative sentence without changing the meaning, you can say 'She is not always not clever'.
Step-by-step explanation:
The original sentence 'She isn't always clever' can be changed into an affirmative sentence without changing the meaning by saying 'She is not always not clever'. This means that she is clever most of the time, but not always. By negating the second part of the sentence, it conveys the same meaning as the original sentence.